Most individuals buy and use a hair shampoo for its cleansing properties. In addition to clean hair, consumers also desire sufficiently conditioned hair that holds a preset configuration. However, present-day hair shampoos generally are formulated with highly effective synthetic surfactants, like anionic surfactants, that primarily clean, as opposed to condition, the hair. Therefore, it is not surprising that hair shampoos usually neither help detangle wet hair nor impart any residual hair conditioning benefits to dry hair, such as the manageability or styleability of hair sets.
Consequently, after shampooing, hair typically is left in a cosmetically unsatisfactory state because an anionic surfactant-based hair shampoo not only removes all of the dirt and soil from the hair, but also removes essentially all of the sebum that is naturally present on the surface of hair fibers. Therefore, the properties of anionic surfactants that effectively cleanse the hair also serve to leave the hair in a cosmetically unsatisfactory condition. In general, therefore, shampooing hair with a hair shampoo composition including anionic surfactants, or nonionic surfactants or amphoteric surfactants, leaves the hair, after rinsing with water, with an undesirable harsh, dull, and dry touch or feel, usually called "creak."
As a result, thoroughly cleansed hair, in either the wet or dry stage, is extremely difficult to comb because individual hair fibers tend to snarl, kink, and interlock with each other. In addition, incompletely dried hair, such as hair dried with a towel, has poor brushing properties. Then, after complete drying, the hair does not set well, and the combing or brushing property of the dried hair remains poor. The dried hair also has undesirable electrostatic properties in a low humidity atmosphere that cause the hair to "fly away," thereby further reducing the brushing property of the hair. The unsatisfactory combing or brushing property of freshly shampooed hair also causes hair damage, such as split ends or hair breakage. In addition, the natural luster and resiliency of the hair is reduced. One approach to overcoming this deficiency in normal shampoos is the use of silicones in the shampoo base. This approach still does not provide durable conditioning benefits.
Accordingly, freshly shampooed hair usually requires a post-shampoo hair treatment with a conditioning composition to improve the unsatisfactory physical and cosmetic condition of the hair. A conditioning composition traditionally is applied separately from the hair shampoo, and usually is a rinse or a cream-like lotion containing a cationic and/or a silicone compound.
However, a major disadvantage of conventional conditioners is a lack of durability of the conditioning properties imparted to the hair. Typically, shampooing the hair substantially eliminates the conditioner from the hair, thereby necessitating a reapplication of the conditioning compound to the hair after each shampoo. Shampooing removes some traditional conditioners from the hair because many conditioners, such as silicones, are not substantive to the hair and are substantially removed by anionic and nonionic surfactants in the shampoo. Other conditioners, such as the cationic quaternary ammonium compounds, are substantive to the hair, but are not covalently bound to the hair. The cationic conditioning compounds are electrostatically bound to sites on the hair having a negative electronic charge. These conditioners also are substantially removed from the hair by anionic surfactants, which have a negative electronic charge and can electrostatically bind to cationic conditioning compounds.
Accordingly, to overcome this disadvantage, investigators have sought compounds capable of covalently bonding to the hair, and methods of covalently bonding the compounds to the hair, to impart durable hair conditioning properties to hair. Investigations in this area have focused on covalently bonding a conditioning compound to the hair during a permanent waving process, especially in connection with the step of reducing the hair with a waving lotion.
In general, the permanent waving of keratin fibers, like human hair, is achieved by first chemically breaking the sulfur-to-sulfur bonds, or disulfide cystine bonds, which are naturally present in human hair, and then reforming the cystine bonds after the hair is configured in a desired hair set. The sulfur-to-sulfur cystine bonds in human hair maintain the hair in a naturally straight or naturally curly configuration, and, in order to permanently reshape the hair into a lasting, different configuration, a substantial number of the sulfur-to-sulfur bonds are broken, and then reestablished after the hair is reconfigured in a desired hair set, such as wrapped around a suitable mandrel or roller. In general, the sulfur-to-sulfur cystine bonds are broken, i.e., the hair is reduced, using a composition termed a waving lotion, which contains a reducing agent. After the reduced hair is reconfigured, the sulfur-to-sulfur cystine bonds are relinked or reestablished while the reduced hair is in the curled formation by contacting the reconfigured hair with a composition termed a neutralizing solution, which contains an oxidizing agent, such as hydrogen peroxide or a water-soluble bromate.
Waving lotions capable of breaking sulfur-to-sulfur cystine bonds in hair traditionally include one or more reducing agents, such as cysteine, acidic sodium hyposulfite, ammonium or sodium bisulfite, thioglycerol, thiolactic acid or a salt thereof, thioglycolic acid or a salt thereof, e.g., a thioglycolate, dithioglycolic acid, and/or a salt thereof, e.g., a dithioglycolate, thiocholine or a salt thereof, a monothioglycolic acid ester, N-acetylcysteamine, cysteamine, or mixtures thereof.
Generally, the waving lotion is applied to freshly shampooed hair, either before or after the hair is configured in a desired hairstyle. When the beauty operator determines that the waving lotion has been in contact with the hair for a sufficient time period to reduce the hair, the hair is rinsed thoroughly. Then a neutralizing solution is applied to the hair to oxidize the hair and reform the sulfur-to-sulfur bonds while the hair is set in the new hairstyle. The neutralizing solution contains an oxidizing agent, such as hydrogen peroxide or a bromate salt, in order to reestablish the sulfur-to-sulfur bonds and set the hair in a new and relatively permanent, e.g., about 2 to 4 months, configuration.
Investigators attempted to take advantage of reduced hair by covalently bonding compounds to the reduced hair to provide a desired effect. For example, GB 1,182,939 discloses contacting the hair with a thiol-functional silicone after the hair is reduced, and prior to oxidizing the hair, to impart a longer lasting hairstyle and retain the natural characteristics of the hair. Similarly, Canadian Patent No. 845,277 discloses application of a thiol-functional silicone to the hair after the hair is reduced.
Varaprath et al. U.S. Pat. No. 5,270,036 and Halloran et al. U.S. Pat. No. 5,279,818 disclose treating reduced hair with a neutralizing solution containing a vinyl-functional silicone. Each patent discloses covalently bonding a vinyl-functional silicone compound to the hair to achieve a benefit of conditioning or hair set retention.
EP 0 295 780 discloses simultaneously applying a reducing agent and a thiol-functional silicone to the hair. EP 0 295 780 discloses that the stepwise method disclosed in above-discussed GB 1,182,939 has disadvantages that are overcome by a method that simultaneously applies the reducing agent and thiol-functional silicone to the hair.
Other investigators applied hair treatment compounds to hair in its natural state. For example, Panandiker et al. U.S. Pat. No. 4,970,067 discloses contacting the hair with a protein having a disulfide-containing amino acid to impart durable hair set retention conditioning properties to treated hair.
Accordingly, prior methods of achieving a covalent bond between hair and a hair-treating compound relied primarily on first reducing the hair, then applying a hair-treating compound that can covalently bond to the reduced hair, and finally oxidizing the reduced hair to form a covalent bond with the hair-treating compound. The compound covalently bonded to the hair typically is hydrophobic. A hydrophobic compound reduces the tendency of hair to absorb moisture, and hence hair set retention is improved. A secondary effect of covalently bonding the compound to hair was to provide conditioning properties.
However, the need still exists for a hair-treating composition that imparts long-lasting conditioning properties to hair without the need to subject the hair to damaging hair reduction and oxidation steps. A majority of consumers consciously avoid the hair damaging effects associated with the reducing step of a permanent wave process, and, accordingly, would not accept an additional time-consuming and damaging process step to impart durable conditioning properties to hair. Furthermore, to a consumer, it is intuitively incongruent to utilize a composition and method of improving the condition of the hair which first requires damaging the hair by a hair reduction step.
Accordingly, to date, the compositions and methods used to impart durable conditioning properties to hair have suffered from poor efficacy, from sacrificing one beneficial hair property in order to achieve another beneficial hair property, and/or from abnormally long times to treat the hair. In addition, the compositions and methods previously used to semipermanently condition the hair suffer from the disadvantages of serious hair damage due to the reduction-oxidation process, coupled with operator error, such as too strong of waving lotion or too long of a contact time. Prior to the present invention, no known method or composition has been employed which effectively treats hair in a few minutes to impart durable conditioning properties that are preserved through at least several shampooings subsequent to the hair treatment.
Therefore, in accordance with the present invention, the durability of hair conditioning properties are surprisingly and unexpectedly improved by a method of contacting the hair with a composition comprising a thiol-functional silicone. The aqueous compositions of the present invention can be applied to the hair at room temperature and provide the benefits and advantages of imparting semipermanent hair conditioning properties to treated hair without the need to damage the hair as a result of harsh reduction and oxidation reactions. As demonstrated more fully hereafter, the methods of the present invention allow treatment of unreduced hair, or reduced hair that has been contacted with a waving lotion. Furthermore, for treated unreduced hair, or for treated hair reduced with a bisulfite salt, an oxidation step can be omitted and durable hair-conditioning properties are observed. Overall, the methods and compositions of the present invention impart esthetically pleasing, semipermanent hair conditioning properties to treated hair, without damaging the hair. The hair-conditioning properties are sufficiently durable to survive through many subsequent shampooings, hence the hair does not have to be conditioned after each shampooing.